The present invention is a storm water filter system for skimming debris from storm water passing through a storm water drain system and more specifically, the present invention is directed towards a storm water filter box having a floatable skimmer therein for capturing floatable debris and trash in the storm water system.
Drain water, which is frequently laden with trash, grass clippings, tree limbs, sand, gravel and other forms of sediment, as well as floatable trash and floatable oil is collected from streets, parking lots and other areas into a storm drain inlet where it is directed into a storm drain pipe system. The drain water laden with trash collected from the streets is fed through an entrance into a storm water catch basin and into a lake or retention pond or the like. The retention pond can tolerate a certain amount of grass clippings collected from parking lots along the streets but debris left in water for a long period of time decays and allows a build up of soluble nutrients, such as nitrates and phosphates, in the water. Thus, it is desirable to remove organic debris from the water collected from the drain water before it enters lakes and retention ponds. At the same time, drain water collects residue oil, and floatable hydrocarbons and organic materials from parking lots and streets and it is also desirable to prevent the floating hydrocarbons being discharged into the lakes or retention ponds. Typically, a skimmer is utilized to capture hydrocarbons and floating liquids within a baffle box to prevent their passing into the outlet.
The present invention is directed towards a skimmer to prevent floatable trash and floatable hydrocarbons from passing out the outlet of a storm water drain system baffle box.
In my prior U.S. Pat. No. 6,869,525 for a Storm Drain Filter System I show a storm drain filter system which includes a skimmer for collecting floating hydrocarbons and for absorbing the hydrocarbons in a hydrocarbon absorbing boom while preventing them from passing out of the skimmer. In my prior U.S. Pat. No. 7,294,256 for a Storm Water Filter System, a storm water filter system is provided for filtering storm water being fed into an in-ground well and uses a fixed skimmer to prevent floating organic debris from entering the discharge into the in-ground recharge well.
The present invention is directed towards an improvement in storm water filter systems in which a filter box has a skimmer for capturing debris and floating organic matter in a storm water filter box and blocking the floating debris from the outlet. Drain water entering a baffle box sometimes flows in very fast and allows the water to rise above a fixed skimmer. This allows floating trash and floating oil and hydrocarbons to go over the top of the skimmer and out the outflow pipe into rivers, lakes or retention ponds. The present invention provides for a floating skimmer that prevents this overflow and forces the drain water passing through the filter box to go under the skimmer and into the outlet.
In the present invention a relative short floating skimmer is used and has the same performance of a much taller fixed skimmer without the head loss associated with a taller skimmer by opening up a larger passageway under the skimmer. A storm water treatment structure that makes use of a floating skimmer can be more easily retrofitted to an existing water shed storm drain system due to the minimal head loss of the shorter skimmer.